Detection of Blister Formation and Evaluation of Pressure Tube/Calandria Tube Contact Location by Ultrasonic Velocity Ratio Measurement Technique

摘要

Presence of hydrogen in zircaloy pressure tube affects the velocity of ultrasound propagation Both longitudinal wave velocity (V_L) and shear wave velocity (V_s) are affected depending on the concentration of hydrogen. Velocity ratio (V_L/V_s) changes as per the concentrations of hydrogen in different locations along the length of pressure tube. A hydride blister which forms at the pressure tube and calandria tube cotnact point is a distinct zone containing hydrogen 2-3 order of magnitude more than the parent matrix and hence, can be detected by sharp change in velocity ratio.